A question about a pre-amp

Location : worcestershire Spotter Watch Member : Yes !!!!

Hi all, Looking for some technical advice on a Jim pre-amp. The instructions for the pre-amp says to power it with a 9v internal batt: or an external 12v supply. I've tried two different brand new adjustable transformers of different makes. In both cases when the transformer is set to 12v it supplys the Jim for a little over 10mins and then cuts out. (Not sure if it's the supply cutting or the Jim). The Jim runs fine for hours when I reduce the voltage to 9v. My question is, Do you think the Jim is working to it's full specification on the 9volt input? It appears to be, in so much as I can notice the difference in the reception on the scanner when I by-pass the Jim, to when it's connected. Can someone tell me please why a 12v external supply is needed, but only a 9v internal one. Many thank's Kindest Jim.. :D ..

p.s It's me writing this, not the pre-amp!! Laughing

.....

Location : Workington Cumbria

Jim

I tried the M-75 on batteries at first but in only lasted a few hours, its now been running on a 12v supply for the last 3yrs with no problems....

Location : worcestershire Spotter Watch Member : Yes !!!!

Thank's for the reply Mick it's appreciated. What I'm really after is will the jim work at maximum on external 9v...Kindest..Jim..

Location : Macclesfield, Cheshire

Hi, have you checked the output of your 12 volt power supply......if it is un-regulated you may have 15-20 volts coming out of it which may be causing the problem with your pre-amp shutting down. The best bet is to try a 12 volt regulated psu.

I have two Jim pre-amps running on 12 volt regulated psu's with no problems

Subject: Re: A question about a pre-amp 2009-01-26, 10:35

also, make sure you remove the 9V battery and put some tape over the connector.

Geoff

Location : Grimsby

hi,
ive had my jim for a year or so now running on a cheapish 12v transformer (with the battery removed and taped up as geoff said)and not had a problem(yet) :) its a good bit of kit i think

dave

Location : worcestershire Spotter Watch Member : Yes !!!!

Many thank's all..Kindest..Jim.. :D